Pressurized fuel system



0a. 23, 1962 SMITLEY 3,059,692

PRESSURIZED FUEL SYSTEM Filed Dec. 30, 1958 FUEL BOWL l4 l2 CARBURETOR ,0 FIG.I. k J/ENGINE K Q a RELIEF VALVE PRESSURE RESPONSIVE 64 VALVE x \I /l\\ l4 94 l w 96 I00 INVENTOR. MARION ,L. SMITLEY ATTORN YS United States Patent 6 3,059,632 PRESSURIZED FUEL SYSTEM Marion L. Smitley, Huntington Woods, Mich., assignor to Holley Carburetor Company, Van Dyke, Mich, a corporation of Michigan Filed Dec. 30, 1958, Ser. No. 783,984 11 Claims. (Cl. 158-365) The present invention relates to a pressurized fuel system.

Present day fuel systems for automotive vehicles employ an atmospheric vent in the fuel tank which allows fuel vapors to escape and which also operates to maintain the tank at atmospheric pressure. The escape of fuel vapors, especially when ambient temperature is relatively high, may result in a substantial loss of fuel and a corresponding apparent reduction in fuel economy for the internal combustion engine.

It is accordingly an object of the present invention to provide a pressurized system including the fuel tank, the fuel pump, and the fuel bowl of the carburetor in which the system i maintained closed up to a predetermined mini-mum pressure after which a pressure relief valve opens to permit escape of fuel vapors from the tank to avoid building up of dangerous pressures.

It is a further object of the present invention to provide a system as described in the preceding paragraph including a pressure responsive valve adapted to close to isolate the float controlled fuel bowl of the carburetor from the relatively higher pressures and thus to prevent forced opening of the float control valve in the fuel bowl of the carburetor.

It is a further object of the present invention to provide a fuel supply system for an internal combustion engine comprising -a fuel tank, a carburetor fuel bowl, a pressure relief valve connected to the fuel tank, and a pressure responsive valve intermediate the tank and bowl effective to prevent transmission of ohjectionally high fuel pressure to the carburetor fuel bowl.

More specifically, it is an object of the present inven tion to provide, in a fuel supply system, a fuel tank relief valve adapted to open when pressure in the fuel tank tends to become sub-atmospheric, which closes when pressure in the fuel tank increases above atmospheric, and which again opens at a predetermined minimum pressure above atmospheric pressure.

It is a further specific object of the present invention to provide in a fuel supply system, a pressure responsive valve adapted to close when fluid pressure applied thereto exceeds a predetermined minimum pressure, and which is adapted to open when pressure at its outlet side falls below atmospheric pressure.

It is a further specific object of the present invention to combine the two valves referred to in the preceding two paragraphs in a system in which the relief valve limits maximum pressure applied to the pressure responsive valve to a value such that subatmospheric pressure as developed by normal operation of a vehicle fuel pump is effective to open the pressure responsive valve.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is a diagrammatic view illustrating the major components of the fuel supply system.

"FIGURE 2 is a vertical sectional view through the pressure relief valve employed in the system.

FIGURE 3 is a vertical sectional view through the pressure responsive valve employed in the system.

FIGURE 4 is a vertical sectional view through the fuel bowl employed in the system.

Patented Oct. 23, 1962 Referring first to FIGURE 1 there is shown an internal combustion engine 10 having a carburetor 12 provided with a fuel bowl 14 adapted to receive fuel through a fuel conduit 16 from a fuel pump 18. The system includes the conventional fuel tank 20 having a filler tube 22 provided with a sealing cap 24. Fuel from the tank 20 flows to a pressure responsive valve 26 and thence to the fuel pump 18. Mounted on the tank 20 by a mounting bracket 28 is a relief valve 30 connected to the tank 20 by a conduit 32.

To insure a continuous flow of fuel from the fuel tank 20 during operation of the engine 10 it is of course necessary to provide for the admission of air into the fuel tank to avoid creation of a vacuum therein which would interfere with the free flow of fuel to the fuel pump. This is accomplished generally by providing an atmospheric vent in the upper part of the fuel tank. The presence of this vent however permits fuel vapors to escape, and particularly when ambient temperature is relatively high this may represent a serious loss of fuel. Obviously, the provision of a check valve which permits the admission of air to the fuel tank but which closes to prevent the escape of fuel vapors would prevent loss of fuel. However, it would be unsafe to provide such a check valve unless provision were also made for opening of the check valve upon attainment of a higher pressure. Also, account must be taken of the usual float control valve in the fuel bowl of the carburetor which may be forced open against the action of the float when pressure of fuel in the fuel line leading to the fuel bowl is excessive. This could lead to flooding and overflowing of the fuel bowl with undesirable results. Since the source of pressure which might lead to this flooding of the carburetor fuel bowl is the fuel tank, this undesirable result may be prevented by providing in the line connecting the fuel tank and fuel bowl a pressure responsive valve adapted to close when undesirably high pressures are permitted to develop within the fuel tank. This pressure responsive valve however must open readily when the engine is started and hence must be responsive to the development of a sub-atmospheric pressure at its outlet side to cause the valve to open.

Referring now to FIGURE 2 there is shown details of the relief valve 30 fulfilling the requirements set forth in the foregoing. The relief valve 30 comprises a lower housing portion 34 having an enlarged chamber 36 therein carrying a valve actuating pin 38 and a coil compression spring 40. Communicating with the chamber 36 is a passage 42 containing a suitable air filter 44 (or alternatively, connected to an air filter) leading to the atmosphere and causing atmospheric pressure to prevail within the chamber 36. The relief valve comprises an upper housing portion 46 shaped to provide a chamber 48 and having an opening 50 for connection to the conduit 32 leading to the upper portion of the fuel tank 20. Intermediate thelower housing portion 34 and the upper housing portion 46 is a flexible diaphragm 52 having a central opening therethrough receiving a neck 5'4 formed on a valve seat element 56, the end of the neck being peened over to grip a washer 58 which forms a seat for the compression spring 40. Received in the valve seat element 56 is a retainer sleeve 60 having its lower portion shaped to engage an O-ring 62 which forms the valve seat. The sleeve 60 is retained in the valve seat element 56 by a pin 64, the sleeve and valve seat element being shaped to provide a plurality of continuous openings 66. Received within the sleeve 60 and normally engaging the valve seat 62 is a ball valve 68'.

It will be observed that in its normal condition the ball valve 68 rests in closing relation on the valve seat 62 by gravity and the compression spring 40 urges the valve seat element 56 upwardly into engagement with the top wall of the upper housing portion 46. If new it is assumed that the engine is started, flow of fuel from the fuel tank 20 tends to reduce air pressure in the space above the fuel in the tank below atmospheric and this results in lifting of the valve 68 by the atmospheric pressure prevailing in the chamber 36. Thus, the valve 68 will continue to open to maintain pressure within the fuel tank 20 substantially at atmospheric pressure during continued operation of the engine 10. When the engine is stopped or if vaporization of fuel within the tank tends to establish pressures above atmospheric pressure within the tank then the valve 68 is prevented from opening and instead, the fluid pressures above atmospheric pressure within the chamber 48 causes downward flexing movement of the flexible diaphragm 52, carrying the valve structure including the valve seat element 56 downwardly therewith against the force of the spring 40. Obviously, the spring 40 is selected to limit the super-atmospheric pressure within the chamber 48 to a definite maximum value. When this maximum value of pressure within the chamber 48 is exceeded downward movement of the valve assembly brings the ball 68 into engagement with the upper end of the pin 38 and further downward movement of the diaaphragm and associated structure results in movement of the valve seat 62 away from the ball valve 68. Thus, the pressure within the tank is relieved and fuel vapor, if it continues to form, is permitted to escape. The setting of the relief valve however may be such that opening of the valve 68 in response to establishment of super-atmospheric pressure within the chamber 48 occurs only under exceptional circumstances so that normally loss of fuel vapors from the tank is avoided.

If the operation of the relief valve to conserve fuel by preventing loss of fuel vapors from the tank is to be most efficient it is of course apparent that the opening of the valve must be prevented until relatively high, although perfectly safe pressures are developed within the fuel tank. Transmission of these pressures to the float controlled fuel bowl 14 of the carburetor would be undesirable since these pressures acting on the needle valve 70 may cause the valve to open against the action of the float 72. In order to prevent such opening of the needle valve 70 with resultant overfilling or flooding of the fuel bowl 14, the pressure responsive valve 26, details of which are best seen in FIGURE 3, is provided. The valve 26 comprises a main body 74 having a threaded recess 76 for receiving a fitting for connection to a conduit leading to the fuel tank 20 and a similar threaded recess 78 for receiving a fitting for connection to a tube leading to the fuel pump 18.

A passage 80 leads from the recess 76 to a cylinder 82, the lower end of the cylinder being in communication with an enlarged recess 84 through a removable valve seat 86. The lower end of the recess 84 is closed by a flexible diaphragm 88, the central portion of the diaphragm being connected to the lower end of a valve stem 90 which at its upper end is connected to a piston-like valve element 92 adapted to move in the cylinder 82, and in its lowermost position to close against the valve seat 86. A cap 94 engages the periphery of the diaphragm 88 and defines therewith a chamber 96 vented to atmosphere by the port 98. Preferably, the cap 94 has a boss 100 pro vided with an opening 102 receiving an extension 104 of the valve stem 90.

The pressure responsive valve 26, as best seen in FIG- URE 1, has its outlet recess 78 connected to a fuel pump 18 which may be of the usual type having a pumping diaphragm, means driven by the engine for moving the diaphragm on a suction stroke, spring means for moving the diaphragm on a pressure stroke, and check valves at opposite sides of a pumping chamber which includes the diaphragm as one wall thereof to insure unidirectional flow of fuel. Assuming that the fuel pump of the type described is not operating, under such condition the fuel pump, if supplied with fuel at an elevated pressure, permits the fuel to flow through the pump toward the engine and accordingly permits pressure to build up on the needle valve 70 of the fuel bowl to the value of the pressure at the inlet side of the fuel pump. On the other hand, initial operation of the pump when the engine is cranked or started immediately tends to draw fuel into its pumping chamber and accordingly will reduce inlet pressure. If it is assumed that the outlet recess 78 of the pressure responsive valve 26 is connected to a fuel pump and that the valve 92 is closed due to attainment of elevated pressures at the inlet side of the pressure responsive valve, the initial pumping stroke of the fuel pump 18 will drop pressure in the chamber 84 to a value below atmospheric pressure. The atmospheric pressure prevailing in the chamber 96 will thus tend to raise or open the valve 92. At the same time the pressure prevailing in the tank 20, which may be super-atmospheric pressure, tends to hold the valve 92 closed. However, the pressure which is allowed to build up in the fuel tank 20 by operation of the relief valve 30 is insufficient to retain the valve 92 closed.

Reviewing the operation of the system in its entirety, when the engine is operating the valve seal element 56 of the relief valve 30 and the pressure responsive valve 26 are in the position shown in FIGURES 2 and 3 respectively, and ball valve 68 will be raised from its seat. If the engine is stopped so that a continued flow of fuel from the tank through the pressure responsive valve 26 and fuel pump 18 to the fuel bowl 14 is terminated generation of fuel vapors within the fuel tank 20 causes an increase in pressure in the tank since the vapors are prevented from escaping due to closure at that time of the ball valve element 68 on the valve seat 62. As the pressure builds up in the fuel tank 20 it is transmitted through the pressure responsive valve and through the fuel pump 18 to the fuel bowl 14. This pressure is however, effective on the diaphragm 88 and operates to close the valve 92 at some pressure below that which would result in forced opening of the needle valve 70. Thereafter, pressure continues to build up in the fuel tank 20 as loss of vapors is prevented by continued closure of the relief valve 30. At some higher temperature, substantially below the development of dangerous pressures within the fuel tank 20, the pressure acting on the diaphragm 52 moves the entire valve assembly including the valve seat 62 and valve 68 downwardly until the ball valve 68 engages the upper end of the stationary pin 38. The development of higher pressures within the fuel tank results in further downward movement of the diaphragm 52 and the assembly connected therewith, causing the valve seat 62 to move downwardly away from the ball valve 68. Initial opening movement of the relief valve of course relieves the pressure within the tank 20 and the ball valve 68 and valve seat 62 cooperate to permit the escape of sufficient fuel vapor to maintain the pressure within the fuel tank at the predetermined upper limit.

If the engine is now started, the initial suction stroke of the fuel pump 18 reduces pressure within the chamber formed by the recess 84 and diaphragm 88 to a value substantially below atmospheric pressure. The area of the diaphragm is such that atmospheric pressure acting in the chamber 96 is effective to overcome the fuel vapor pressure acting on the upper end of the valve 92, thus lifting the valve and permitting fuel to flow through the pressure responsive valve 26 to the pump 18. Continued operation of the pump will of course quickly reduce pressure in the fuel tank to atmospheric pressure at which time the valve 68 will be drawn upwardly by suction to maintain pressure within the fuel tank substantially at atmospheric pressure.

It is important to note the coaction between the several valves and components of the system. Basically, it is necessary to isolate the fuel bowl from the fuel tank if the escape of fuel vapors from the fuel tank are to be prevented so that substantial pressure is developed within the fuel tank. At the same time, the system must provide for relief of these pressures to prevent them attaining a dangerous value. The maintaining of vapor pressure within the fuel tank at a substantial value above that safe to apply to the carburetor fuel bowl poses a problem in the opening of the pressure responsive valve at the proper time to permit flow of fuel to resume. The structure described in the foregoing solves all of the problems associated with the foregoing operation in a simple and effective manner.

The drawing and the foregoing specification constitute a description of the improved pressurized fuel system in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

l. A fuel supply system for an internal combustion engine including a carburetor having a fuel bowl, a floatcontrolled inlet valve for said bowl, a fuel tank, a fuel passage connecting said tank and inlet valve, a fuel pump in said passage, a fuel valve in said passage between said tank and said pump, said fuel valve comprising pressureresponsive means resonsive to attainment of a predetermined minimum pressure in said passage to close said valve, a pressure relief valve connected to said tank, said pressure-responsive means being effective upon initiation of pump operation to open said fuel valve against any pressure in said passage between said tank and fuel valve less than required to open said relief valve.

2. A fuel supply system for an internal combustion engine includin-ga carburetor having a fuel bowl, a floatcontrolled inlet valve forsaid bowl, a fuel tank, a fuel passage connecting said tank and inlet valve, a fuel pump in said passage, a fuel valve in said passage between said tank and said pump, said fuel valve comprising a pressure responsive diaphragm exposed at one side to atmospheric pressure and at the other side to pressure within said passage between said fuel valve and fuel pump and responsive to attainment of a predetermined minimum pressure in said passage to close said valve, a pressure relief valve connected to said tank, said fuel valve comprising a valve element upstream from its valve seat whereby pressure in said tank when said fuel valve is closed tends to hold said'fuel valve on its seat, said pressure-responsive means being effective upon initiation of pump operation to open said fuel valve against any pressure in said passage between said tank and fuel valve less than required to open said relief valve.

3. A fuel supply system for an internal combustion engine provided with a carburetor including a fuel bowl having a float-controlled valve, a sealed fuel tank, a fuel passage connecting said tank and bowl, a normally closed pressure relief valve connecting said tank to atmosphere, a fuel valve in said passage between said tank and bowl, a fuel pump in said passage between said fuel valve and said bowl, said pump being of the type providing for flow of fuel from said tank to said bowl when pressure in said tank is elevated while said pump is idle, means for opening said relief valve when pressure within said tank falls below atmospheric, and means for opening said relief valve when pressure in said tank reaches a predetermined value substantially above atmospheric, said fuel valve in the passage between said tank and bowl comprising pressure responsive means for closing said fuel valve at a predetermined pressure in said fuel passage above atmospheric but substantially below the value at which said relief valve opens due to a pressure build-up in the tank, said pressure responsive means being effective to open said fuel valve if closed upon reduction of pressure in the portion of the fuel passage between said fuel valve and pump caused by initial pump operation.

4. A fuel supply system for an internal combustion engine provided with a carburetor including a fuel bowl having a float controlled valve operable at and below a limiting pressure to control flow of fuel into said fuel bowl, a sealed fuel tank, a fuel passage connecting said tank and bowl and including said float controlled valve, a

fuel pump in said passage said pump being of the type providing for flow of fuel from said tank to said bowl when pressure in said tank is elevated while said pump is idle, means responsive to development of sub-atmospheric pressure in said tank for connecting said tank to atmosphere, means responsive to development of relati=vely high super-atmospheric pressure within said tank for connecting said tank to atmosphere, said aforementioned means being operable to seal said tank from atmosphere while pressure within said tank is between atmospheric pressure and said relatively high super-atmospheric pressure, and means responsive to a build-up of pressure in said fuel passage on the downstream side of said fuel pump to close the passage connecting said tank and fuel bowl at pressures above the limiting pressure of said float controlled valve, the limiting pressure of said float controlled valve being substantially below the said relatively high super-atmospheric pressure at which said tank is connected to atmosphere.

5. A fuel supply system for an internal combustion engine comprising a carburetor having a fuel bowl provided with a float-controlled inlet valve, a sealed fuel tank, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, and a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined super-atmospheric pressure in the tank to close said passage, said fuel valve including means responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage.

6. A fuel supply system for an internal combustion engine comprising a carburetor having a fuel bowl provided with a float-controlled inlet valve, a sealed fuel tank, a pressure responsive relief valve connected to said tank to vent vapors to atmosphere, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined super-atmospheric pressure in the tank to close said passage, said fuel valve including means responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage, and said relief valve being responsive to open at a predetermined pressure in said tank which is substantially above the aforesaid predetermined super-atmospheric pressure in the tank required to close said passage.

7. A fuel supply system for an internal combustion engine comprising a carburetor having a fuel bowl provided with a float-controlled inlet valve, a sealed fuel tank, a pressure responsive relief valve connected to said tank to vent vapors to atmosphere, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined super-atmospheric pressure in the tank to close said passage, said fuel valve including means responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage, said relief valve being responsive to open at a predetermined pressure in said tank which is substantially above the aforesaid predetermined super-atmospheric pressure in the tank required to close said passage, and means in said relief valve for opening said tank to atmosphere when pressure within said tank falls below atmospheric.

8. A fuel supply system for an internal combustion engine including a carburetor having a fuel bowl, a floatcontrolled inlet valve for said bowl, a sealed fuel tank including valve means providing for the development of a range of super-atmospheric pressures within said tank between atmospheric pressure and a limiting super-atmospheric pressure, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined superatmospheric pressure within the range of pressures developed within said tank to close said passage, and being responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage.

9. A fuel supply system for an internal combustion engine including a carburetor having a fuel bowl, a floatcontrolled inlet valve for said bowl, a sealed fuel tank including valve means providing for the development of a range of super-atmospheric pressures within said tank between atmospheric pressure and a limiting super-atmospheric pressure, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined superatrnospheric pressure within the range of pressures developed within said tank to close said passage and being responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage, said valve means including means effective to vent said tank to atmosphere at sub-atmospheric pressure.

10. A fuel supply system for an internal combustion engine including a carburetor having a fuel bowl, a floatcontrolled inlet valve for said bowl, a sealed fuel tank including valve means providing for the development of a range of super-atmospheric pressures within said tank between atmospheric pressure and a limiting super-atmospheric pressure, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined superatmospheric pressure within the range of pressures developed within said tank to close said passage and being responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage, said valve means including means effective to vent said tank to atmosphere upon the attainment of the aforesaid limiting super-atmospheric pressure.

11. A fuel supply system for an internal combustion engine including a carburetor having a fuel bowl, a floatcontrolled inlet valve for said bowl, a sealed fuel tank including valve means providing for the development of a range of super-atmospheric pressures within said tank between atmospheric pressure and a limiting super-atmospheric pressure, a fuel supply passage connecting said tank to said bowl, a fuel pump in said passage, a fuel valve in said passage between said pump and said tank, said fuel valve being responsive to a predetermined superatmospheric pressure within the range of pressures developed within said tank to close said passage and being responsive to a sub-atmospheric pressure at the inlet side of said pump effective to open said passage, said valve means including means effective to vent said tank to atmosphere at sub-atmospheric pressure and including means effective to vent said tank to atmosphere upon the attainment of the aforesaid limiting super-atmospheric pressure, said aforementioned means being operable to seal said tank from atmosphere while pressure within said tank is in the aforesaid range of super-atmospheric pressures.

References Cited in the file of this patent UNITED STATES PATENTS 2,297,129 Bohnstedt Sept. 29, 1942 2,364,605 Curtis Dec. 12, 1944 2,693,821 Cornelius Nov. 9, 1954 2,737,202 Baldwin et a1. Mar. 6, 1956 2,845,088 Crausrnan et a1 July 29, 1958 

